The instant invention relates to filtering systems, and specifically to a filtering system which is intended for use between a septic tank and a drain field.
Septic tanks provide a means of domestic and small commercial sewerage disposal in many parts of the world where municipal or other sewerage treatment facilities are not available. Such systems create pollution problems, however, when they are located in areas which have particularly high water tables or in areas where the water supply comes from ground water. In such instances, the effluent from the septic tanks, which traditionally enters a drain field and is dispersed in the land surrounding the dwelling or business establishment which owns the septic tank, will leach through the soil and will ultimately enter the ground water supply. Such effluent will ultimately contaminate the ground water supply. If the effluent from a septic tank were sufficiently free of biological and inorganic contaminates, such entry into the ground water would not contaminate the ground water supply.
One technique to decrease the level of biological oxygen demand (BOD) and total suspended solids (TSS) in septic tank effluent is to process the effluent through a sand filter prior to allowing the effluent to enter the drain field. Such a system significantly reduces the BOD and TSS content in the effluent, however, organic contaminates, such as fecal coliform, and nitrogen, in its various forms, will not completely be removed by a sand filter, and will ultimately enter the ground water. The presence of fecal coliform in the ground water can result in serious illness if such water is consumed, untreated, by human beings and domestic animals. Additionally, the usual sand filter occupies an area of approximately 400 square feet. Although that area represents a structure of 20 feet on a side, there are many instances where the yard surrounding a dwelling does not provide that much available surface area to allow the installation of such a filter. Also, a conventional sand filter becomes clogged after a relatively short period of time, requiring replacement of the filtering media.
An object of the instant invention is to provide a filter for use between a septic tank and a drain field which is of compact size.
Another object of the instant invention is to provide a filter which will reduce the BOD, TSS and nitrogen content in the effluent discharged from a septic tank prior to the effluent entering a drain field.
A further object of the instant invention is to provide a filter which will provide simultaneous anaerobic and aerobic treatment of septic tank effluent.
Another object of the instant invention is to provide a filter which is relatively inexpensive to install and maintain, and which will purify septic tank effluent with minimal maintenance or attention.